At present, with development of Dense Wavelength Division Multiplexing (DWDM) technologies, an adjustable laser occupies an important position in smart optical networks as it can provide light waves with greater flexibility and faster supply speed for the operator. However, in actual applications, even when the working condition is unchanged, the wavelength of the light waves generated by the adjustable laser may generally drift 0.03-0.04 nm, and may even offset 1 channel in extreme cases; therefore, if the adjustable laser is intended for large-scale commercial use, it is necessary to use an effective wavelength lock technology to improve wavelength stability of the adjustable laser.